feat(frontend): add question search

frontend/src/app/questions/page.tsx

@@ -94,6 +94,7 @@ export default async function QuestionsPage({
           patterns={patternsResponse.items}
           currentCategory={params.category}
           currentPattern={params.pattern}
+          currentSearch={params.search}
         />
       </div>
 
@@ -118,7 +119,7 @@ export default async function QuestionsPage({
                   params.difficulty ? `&difficulty=${params.difficulty}` : ""
                 }${params.category ? `&category=${params.category}` : ""}${
                   params.pattern ? `&pattern=${params.pattern}` : ""
-                }`}
+                }${params.search ? `&search=${encodeURIComponent(params.search)}` : ""}`}
                 className={`px-3 py-1 rounded ${
                   page === questionsResponse.page
                     ? "bg-[var(--primary)] text-[var(--primary-foreground)]"

frontend/src/components/questions/question-filters.tsx

@@ -0,0 +1,161 @@
+"use client";
+
+import { useRouter, useSearchParams } from "next/navigation";
+import { useCallback, useState, useEffect, useRef } from "react";
+import { Search } from "lucide-react";
+import type { Category, Pattern } from "@/types";
+
+interface QuestionFiltersProps {
+  categories: Category[];
+  patterns: Pattern[];
+  currentCategory?: string;
+  currentPattern?: string;
+  currentSearch?: string;
+}
+
+export function QuestionFilters({
+  categories,
+  patterns,
+  currentCategory,
+  currentPattern,
+  currentSearch,
+}: QuestionFiltersProps) {
+  const router = useRouter();
+  const searchParams = useSearchParams();
+  const [searchValue, setSearchValue] = useState(currentSearch || "");
+  const debounceRef = useRef<NodeJS.Timeout | null>(null);
+
+  // Update local state when URL changes
+  useEffect(() => {
+    setSearchValue(currentSearch || "");
+  }, [currentSearch]);
+
+  const handleSearchChange = useCallback(
+    (e: React.ChangeEvent<HTMLInputElement>) => {
+      const value = e.target.value;
+      setSearchValue(value);
+
+      // Debounce the URL update
+      if (debounceRef.current) {
+        clearTimeout(debounceRef.current);
+      }
+
+      debounceRef.current = setTimeout(() => {
+        const params = new URLSearchParams(searchParams.toString());
+        if (value.trim()) {
+          params.set("search", value.trim());
+        } else {
+          params.delete("search");
+        }
+        params.delete("page");
+        router.push(`/questions?${params.toString()}`);
+      }, 300);
+    },
+    [router, searchParams]
+  );
+
+  // Cleanup timeout on unmount
+  useEffect(() => {
+    return () => {
+      if (debounceRef.current) {
+        clearTimeout(debounceRef.current);
+      }
+    };
+  }, []);
+
+  const handleCategoryChange = useCallback(
+    (e: React.ChangeEvent<HTMLSelectElement>) => {
+      const params = new URLSearchParams(searchParams.toString());
+      if (e.target.value) {
+        params.set("category", e.target.value);
+      } else {
+        params.delete("category");
+      }
+      params.delete("page");
+      router.push(`/questions?${params.toString()}`);
+    },
+    [router, searchParams]
+  );
+
+  const handlePatternChange = useCallback(
+    (e: React.ChangeEvent<HTMLSelectElement>) => {
+      const params = new URLSearchParams(searchParams.toString());
+      if (e.target.value) {
+        params.set("pattern", e.target.value);
+      } else {
+        params.delete("pattern");
+      }
+      params.delete("page");
+      router.push(`/questions?${params.toString()}`);
+    },
+    [router, searchParams]
+  );
+
+  return (
+    <>
+      <div className="space-y-1">
+        <label
+          htmlFor="search-filter"
+          className="text-sm text-[var(--muted-foreground)]"
+        >
+          Search
+        </label>
+        <div className="relative">
+          <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 h-4 w-4 text-[var(--muted-foreground)]" />
+          <input
+            id="search-filter"
+            type="text"
+            value={searchValue}
+            onChange={handleSearchChange}
+            placeholder="Search questions..."
+            className="pl-8 pr-3 py-1 rounded text-sm bg-[var(--card)] border border-[var(--border)] w-48"
+          />
+        </div>
+      </div>
+
+      <div className="space-y-1">
+        <label
+          htmlFor="category-filter"
+          className="text-sm text-[var(--muted-foreground)]"
+        >
+          Category
+        </label>
+        <select
+          id="category-filter"
+          value={currentCategory || ""}
+          onChange={handleCategoryChange}
+          className="px-3 py-1 rounded text-sm bg-[var(--card)] border border-[var(--border)]"
+        >
+          <option value="">All Categories</option>
+          {categories.map((cat) => (
+            <option key={cat.id} value={cat.slug}>
+              {cat.name} ({cat.question_count})
+            </option>
+          ))}
+        </select>
+      </div>
+
+      <div className="space-y-1">
+        <label
+          htmlFor="pattern-filter"
+          className="text-sm text-[var(--muted-foreground)]"
+        >
+          Pattern
+        </label>
+        <select
+          id="pattern-filter"
+          value={currentPattern || ""}
+          onChange={handlePatternChange}
+          className="px-3 py-1 rounded text-sm bg-[var(--card)] border border-[var(--border)]"
+        >
+          <option value="">All Patterns</option>
+          {patterns.map((pat) => (
+            <option key={pat.id} value={pat.slug}>
+              {pat.name} ({pat.question_count})
+            </option>
+          ))}
+        </select>
+      </div>
+    </>
+  );
+}